Modern residential and commercial irrigation systems include subterranean plastic branch pipes that each feed water to multiple sprinklers mounted on risers. Pressurized water is fed to the branch pipes via solenoid actuated values which are energized by an electronic irrigation controller. The controller executes a watering program consisting of pre-programmed run and cycle times for all of the sprinklers on each of the branch pipes, which are collectively referred to as a station.
The sprinklers that are used in residential and commercial irrigation systems fall into several basic categories. Spray-type sprinklers are used for close-in watering and project a fan-shaped pattern of water which is either full circle or some division thereof, e.g. ninety degrees. Adjustable arc spray nozzles have also been used for many years. Rotor-type sprinklers are used where large area coverage is desired and typically eject from a nozzle a single, relatively robust inclined stream of water as much as sixty feet or more. The nozzle is oscillated through an adjustable arc utilizing turbine, gear reduction and reversing mechanisms. Rotor-type sprinklers often have replaceable nozzles to vary the precipitation rate, i.e. gallons per minute (GPM), of the sprinkler. Some rotor-type sprinklers used on golf courses have built-in valves. Rotary stream sprinklers simultaneously eject a plurality of smaller inclined streams of water. They are useful in applications where more coverage is needed than can be provided by a spray-type sprinkler, and usually less than that provided by a large rotor-type sprinkler. They also eject an aesthetically pleasing array of slowly moving water streams. A modern rotary stream sprinkler has a pop-up riser with an inverted frusto-conical distributor head. Water is channeled upwardly through a flow-adjustable orifice and impinges on the underside of the distributor head. The distributor head has spiral grooves that form the rotary streams. A viscous damper mechanism ensures that the distributor head turns slowly so that the reach of the multiple streams is not unduly reduced. The shape of the orifice can be varied to adjust the pattern of coverage of the rotary streams.
Rotary stream sprinklers have evolved over many decades. U.S. Pat. No. 1,764,570 granted to J. C. Lohman on Jun. 17, 1930 discloses a sprinkler with an inverted frusto-conical body with a series of longitudinally and spirally extending flutes. Streams of water passing upwardly through an annular series of apertures are directed against the flutes and cause the body to rotate. The rotary stream sprinkler of Lohman can be used with an underground irrigation system. U.S. Pat. No. 2,493,595 granted Jan. 3, 1950 to N. M. Rieger discloses a similar rotary stream sprinkler adapted for hose-end use.
U.S. Pat. No. 3,854,664 granted Dec. 17, 1974 to Edwin J. Hunter discloses a sprinkler with a rotating head that directs a plurality of rotating streams over an area to be watered. The streams are formed in nozzles in the rotating head. The rotating head has inlets to the nozzles on one end with cooperate with a keyed orifice plate which acts as a valve for communicating water to the nozzles. Orifice plates with various types of openings may be substituted to obtain any desired spray pattern. An impeller is actuated by the water flow to rotate the nozzle through a transmission.
U.S. Pat. No. 4,471,908 granted Sep. 18, 1984 to Edwin J. Hunter discloses a similar sprinkler having V-shaped nozzles in a cylindrical rotating head. The nozzle inlet openings cooperate with an orifice plate to vary the nozzle openings to the source of pressurized water, delivering streams of varying length and volume from the rotating head. The orifice in the plate defines the spray pattern to be produced by the streams issuing from the nozzles in the rotating head.
U.S. Pat. No. 4,815,662 granted Mar. 28, 1989 to Edwin J. Hunter discloses a rotary stream sprinkler with a damping device connected to the rotary head for controlling the rotational velocity of the head. U.S. Pat. No. 4,842,201 granted Jun. 27, 1989 to Edwin J. Hunter discloses a rotary stream sprinkler in which one or more arcuate passages are configured to control the volume and pressure of primary stream of water delivered to rotary distributing head.
U.S. Pat. No. 4,867,379 granted Sep. 19, 1989 to Edwin J. Hunter discloses a rotary stream sprinkler with a multi-passage flow control unit. U.S. Pat. No. 4,898,332 granted Feb. 6, 1990 to Edwin J. Hunter discloses a rotary stream sprinkler with a flow control unit having a variable restriction in a passage to or more arcuate passages. See also U.S. Pat. Nos. 4,932,590; 4,967,961; and 4,971,250, all granted to Edwin J. Hunter.
More recently U.S. Pat. No. 6,651,905 granted Nov. 25, 2003 to George Sesser et al. discloses an adjustable arc rotary stream sprinkler that includes an arc adjustment ring rotatably mounted on a base for rotating the nozzle relative to a stem for adjusting the arcuate discharge orifice. A throttle member is secured to the upstream end of a shaft such that rotation of the shaft causes the throttle to move relative to a portion of the stem, thereby adjusting the flow rate through the nozzle.
The type, placement and precipitation rates for the sprinklers of an irrigation system are usually selected when the system is designed or installed by a contractor. The goal is to uniformly distribute the optimum amount of water over a given area. The optimum precipitation rate provided by each sprinkler should preferably fall within plus or minus one-quarter GPM. The precipitation rate of a sprinkler is largely determined by the size and configuration of its nozzle orifice(s), although variations result from fluctuations in water pressure that cannot be fully negated with pressure regulators.
There is an ever growing need to conserve water, particularly in the Western United States. The watering program of an irrigation controller can also be optimized to ensure green turf and landscaping are maintained while using the minimum amount of water. In some cases, irrigation controllers are augmented with rain interrupt sensors and evapotranspiration data to modify their cycle and run times to accommodate weather changes. The amount of water conservation achievable through the design and dynamic re-programming of the irrigation controller has nearly been exhausted. Therefore, it is time to re-direct attention to the efficiency of the sprinklers themselves. Conventional rotary stream sprinklers typically distribute one to two GPM over an area approximately sixty feet wide.
It would be desirable to provide an improved rotary stream sprinkler that could uniformly water a relatively large area with substantially less water than conventional rotary stream sprinklers. Such a rotary stream sprinkler could also be used in place of multiple spray-type sprinklers and small rotor-type sprinklers and multiple valves. Such a sprinkler should have the capability for precisely tailoring its water distribution pattern including its shape and size.